I am working on editing some old C++ code that uses global arrays defined like so:
int posLShd[5] = {250, 330, 512, 600, 680};
int posLArm[5] = {760, 635, 512, 320, 265};
int posRShd[5] = {765, 610, 512, 440, 380};
int posRArm[5] = {260, 385, 512, 690, 750};
int posNeck[5] = {615, 565, 512, 465, 415};
int posHead[5] = {655, 565, 512, 420, 370};
I want to make all of these arrays private members of the Robot class defined below. However, the C++ compiler does not let me initialize data members when I declare them.
class Robot
{
private:
int posLShd[5];
int posLArm[5];
int posRShd[5];
int posRArm[5];
int posNeck[5];
int posHead[5];
public:
Robot();
~Robot();
};
Robot::Robot()
{
// initialize arrays
}
I want to initialize the elements of these six arrays in the Robot() constructor. Is there any way to do this other than assigning each element one by one?
In the static method, the method can only access only static data members and static methods of another class or same class but cannot access non-static methods and variables.
Member initialization Non-static data members may be initialized in one of two ways: 1) In the member initializer list of the constructor.
Initialisation of Data members As you can see, the variables get their default value in the place of declaration. There's no need to set values inside a constructor. The feature is called non-static data member initialization, or NSDMI in short.
To initialize the const value using constructor, we have to use the initialize list. This initializer list is used to initialize the data member of a class. The list of members, that will be initialized, will be present after the constructor after colon.
If your requirement really permits then you can make these 5 arrays as static
data members of your class and initialize them while defining in .cpp file like below:
class Robot
{
static int posLShd[5];
//...
};
int Robot::posLShd[5] = {250, 330, 512, 600, 680}; // in .cpp file
If that is not possible then, declare this arrays as usual with different name and use memcpy()
for data members inside your constructor.
Edit:
For non static members, below template
style can be used (for any type like int
). For changing the size, simply overload number of elements likewise:
template<size_t SIZE, typename T, T _0, T _1, T _2, T _3, T _4>
struct Array
{
Array (T (&a)[SIZE])
{
a[0] = _0;
a[1] = _1;
a[2] = _2;
a[3] = _3;
a[4] = _4;
}
};
struct Robot
{
int posLShd[5];
int posLArm[5];
Robot()
{
Array<5,int,250,330,512,600,680> o1(posLShd);
Array<5,int,760,635,512,320,265> o2(posLArm);
}
};
The array initialization has now become trivial:
class Robot
{
private:
int posLShd[5];
...
public:
Robot() : posLShd{0, 1, 2, 3, 4}, ...
{}
};
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